11.17登录页面

using SnacksInventorySystem;
using System;
using System.Data.SqlClient;
using System.Drawing;
using System.Windows.Forms;

namespace lsd
{
    public partial class FormLogin : Form
    {
        public FormLogin()
        {
            InitializeComponent();
            InitializeUI();
        }

        private void InitializeUI()
        {
            // 设置窗口标题
            Text = "零食店进销存管理系统 - 登录";
            // 设置窗口大小
            Width = 300;
            Height = 200;
            // 设置窗口起始位置为屏幕中央
            NewMethod();

            // 创建用户名标签
            Label labelUsername = new Label();
            labelUsername.Text = "用户名:";
            labelUsername.Location = new Point(20, 20);
            labelUsername.AutoSize = true;

            // 创建用户名输入框
            textBoxUsername = new TextBox();
            textBoxUsername.Location = new Point(80, 20);
            textBoxUsername.Width = 150;

            // 创建密码标签
            Label labelPassword = new Label();
            labelPassword.Text = "密码:";
            labelPassword.Location = new Point(20, 60);
            labelPassword.AutoSize = true;

            // 创建密码输入框（设置密码字符显示为黑点）
            textBoxPassword = new TextBox();
            textBoxPassword.Location = new Point(80, 60);
            textBoxPassword.Width = 150;
            textBoxPassword.PasswordChar = '*';

            // 创建登录按钮
            Button buttonLogin = new Button();
            buttonLogin.Text = "登录";
            buttonLogin.Location = new Point(100, 100);
            buttonLogin.Click += buttonLogin_Click;

            // 创建用于显示错误提示信息的标签
            labelError = new Label();
            labelError.Location = new Point(20, 140);
            labelError.AutoSize = true;
            labelError.ForeColor = Color.Red;

            // 将各控件添加到登录窗口
            Controls.Add(labelUsername);
            Controls.Add(textBoxUsername);
            Controls.Add(labelPassword);
            Controls.Add(textBoxPassword);
            Controls.Add(buttonLogin);
            Controls.Add(labelError);
        }

        private static void NewMethod()
        {
          
        }

        private void buttonLogin_Click(object sender, EventArgs e)
        {
            string username = textBoxUsername.Text;
            string password = textBoxPassword.Text;
            // 这里假设连接到本地的SQL Server数据库，实际根据你的配置修改连接字符串
            string connectionString = "Data Source=LAPTOP-ODQTAPDG\\MSSQLSERVER01;Initial Catalog=SnacksInventoryDB;User ID=root;Password=123456";
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                string query = "SELECT COUNT(*) FROM Users WHERE Username = @Username AND Password = @Password";
                SqlCommand command = new SqlCommand(query, connection);
                command.Parameters.AddWithValue("@Username", username);
                command.Parameters.AddWithValue("@Password", password);
                try
                {
                    connection.Open();
                    int count = (int)command.ExecuteScalar();
                    if (count > 0)
                    {
                        // 登录成功，打开主界面
                        FormMain formMain = new FormMain();
                        formMain.Show();
                        this.Hide();
                    }
                    else
                    {
                        labelError.Text = "用户名或密码错误，请重新输入！";
                    }
                }
                catch (Exception ex)
                {
                    labelError.Text = "登录出错：" + ex.Message;
                }
            }
        }
        private void FormLogin_Load(object sender, EventArgs e)
        {
            // 在这里编写登录页面加载时要执行的代码逻辑
            // 例如设置窗口的背景颜色
            this.BackColor = Color.White;
            // 或者对用户名输入框设置初始提示文本（仅示例，实际可能有更好方式）
            textBoxUsername.Text = "请输入用户名";
            textBoxUsername.ForeColor = Color.Gray;
            textBoxUsername.GotFocus += (s, args) =>
            {
                if (textBoxUsername.Text == "请输入用户名")
                {
                    textBoxUsername.Text = "";
                    textBoxUsername.ForeColor = Color.Black;
                }
            };
            textBoxUsername.LostFocus += (s, args) =>
            {
                if (string.IsNullOrEmpty(textBoxUsername.Text))
                {
                    textBoxUsername.Text = "请输入用户名";
                    textBoxUsername.ForeColor = Color.Gray;
                }
            };

            // 还可以加载一些比如记住密码相关的数据（如果有此功能）等，根据实际业务逻辑添加代码
        }

        private TextBox textBoxUsername;
        private TextBox textBoxPassword;
        private Label labelError;
    }
  
 }

namespace lsd
{
    partial class FormLogin
    {
        /// <summary>
        /// 必需的设计器变量。
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// 清理所有正在使用的资源。
        /// </summary>
        /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows 窗体设计器生成的代码

        /// <summary>
        /// 设计器支持所需的方法 - 不要修改
        /// 使用代码编辑器修改此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {
            this.components = new System.ComponentModel.Container();
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(300, 200);
            this.IsMdiContainer = false;
            this.MainMenuStrip = null;
            this.Name = "FormLogin";
            this.Text = "零食店进销存管理系统 - 登录";
            this.Load += new System.EventHandler(this.FormLogin_Load);
        }

        #endregion
    }
}